Screw type air pump



July 26, 1949; w, w. PAGET 2,477,004

SCREW TYPE AIR PUMP Filed Oct. 20, 1945 5 Sheets-Sheet 1 o o n E fiuzewor:

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SCREW TYPE AIR PUMP Filed Oct. 20, 1945 5 Sheets-Sheet 2 July 26, 1949. w. w. PAGET I 2,477,004

SCREW TYPE AIR PUMP Filed Ogt. 20. 1945 5 Sheets-Sheet 3 I nvenwn Zl/z/n la Paget.

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SCREW TYPE AIR PUMP 5 Sheets-Sheet 4 Filed 001:. 20. 1945 July 26, 1949. w. w. PAGET SCREW TYPE AIR I UMP 5 Sheets-Sheet 5 Filed Oct. 20, 1945 ill (Zn Z1], Paget. y SIMMC m)- Patented July 26, 1949 SCREW TYPE AIR PULIP Win W. Paget, Michigan City, Ind., assignor to Joy Manufacturing Company, a corporation of Pennsylvania Application October 20, 1945, Serial No. 623,485 3 Claims. (01.230-443) My invention relates to air pumping apparatus, and more particularly to pumping apparatus of the rotary screw type.

In a rotary screw type pumping apparatus there is obtained a longitudinal thrust on the rotors by the action of the fluid on the latter. The rotors of a high speed compressor of the screw type are desirably arranged so as to provide between themselves a slight clearance which should be maintained under all loads. In order that the rotors may be prevented from moving longitudinally under the thrust of the fluid and coming into contact with each other, it is de-.'

sirable that there be provided a means which operates to balance the longitudinal thrust on the rotors and to prevent any movement of the rotors relative to each other.

An object of my invention is to provide an improved pumping apparatus. Another object is to provide improved means for balancing the longitudinal thrust on the rotors of a rotary screw type compressor. Still another object is to provide improved driving gears for the rotors of a screw type compressor. Yet another object is to provide for the rotors of a screwjtype compressor improved driving means including intermeshing gears fixed to the rotors and having teeth arranged at angles corresponding in hand and lead to the angles of the rotors. Other objects will appear in the course of the following description.

This application is a continuation-in-part of my application, Ser. No. 452,299, filed July 25, 1942, Air pumping apparatus, and of my application, Ser. No. 458,641, filed September 17, 1942, Air pumping apparatus.

There is shown in the accompanying drawing for purposes of illustration one form whichthe invention may assume in practice.

In this drawing,

Fig. 1 is a side elevational view of a complete Dumping apparatus.

Fig. 2-is an elevational view of the pumping apparatus as viewed from the left-hand end in Fi 1.

Fig. 3 is an elevational view of the pumping :pparatus as viewed from the right-hand end in Fig. 4 is an enlarged horizontal longitudinal sectional view on the planes of the line 4-4 of Fig. 1.

Fig. 5 is a fragmentary vertical section, with parts shown in elevation, taken on the line 5- of Fig. 4.

, v 2 Fig. 6 is a vertical sectional view taken on the plane of the line 6-6 of Fig. 5.

Fig, 7 isan enlarged fragmentary sectional .view taken on the line 'l-| of Fi 5.

Fig. 8 is an enlarged cross-sectional view taken on the line H of Fig. 1.

Fig. 9 is a cross-sectional view taken on the plane of the line 9-9 of Fig. 4.

Fig. 10 is a vertical sectional view. takenon the line 10-45 of Fig. 4. v

There is shown in the illustrative embodiment of the invention a pumping apparatus, generally designated 1, comprising a casing part 3 containing a pair of coacting rotors 4 and 5. The rotor 4 is a male rotor and has four helically arranged lobes 1, and the rotor 5 is a female rotor and has, in the form shown, six helically arranged grooves 8 each adapted to cooperate with the lobes of the rotor 4. The casing 3 is provided with an intake chamber ID with which an intake passage ll provided with suitable strainer or other devices, not shown, for preventing the ingress of harmful material, communicates, and the intake chamber communicates with the right-hand, low pressure end of the rotors, and also for .a substantial part of the length of the rotors communicates with the back portions thereof, so to speak, the portions at the opposite side of the plane which includes the rotor axes, from the discharge. The intake chamber It also includes, as shown in Fig. 10, curved recesses l9 extending substantial distances arcuately, the extent of these recesses being such that, in the illustrative embodiment shown, the intake chamber and its component recesses Ill provide intake communication with the rotor chambers over arcs of considerably more than .The casing 3 is provided at the left-hand (high pressure) end of the rotors with a discharge chamber 14 which communicates with the high pressure ends of the rotor chambers, as shown in Fig. 9.

The rotors are adapted to operate with space packing; that is to say, they are maintained in such relation to each other that there is no actual contact between them. At the high pressure ends of. the rotors 4 and 5 are stub shafts l5 and it which are mounted in bearings 18 and I9 supported by a head member 20 attached to the end of the casing 3,.as by screws 2|. At the low pressure ends of the rotors are stub shafts, not shown, supported by bearings mounted in an end casing portion 23 formed integral with the casing part 3. Splined to the stub shafts l5 and ii at 24 and 25, respectively, are helical gears 25 and 21 meshing with each other and shown. The. clutch mechanism, F means, a; fluid supply-means forr'the A, means-and control meanstherefortare shown-and operating to maintain the rotors out of contact with each other. Thegear 28 ismade'up of two parts 28 and 30 which are adjusted ang'ularly relative to each other until any backlash between the gears 2| and 21 is almost completely }ellmi-' pm wn herein as being substantially when the clutch'is applied, the gear '2 is connected directly to the shaft 32 and drives the a sear II. The gear 28 is driven with the Bear II and drives in turn the gear 21, the rotors l and .Iv being driven with the gears and 21. It will beseen thatthe gear ,2! will bye-rotated faster than the member u and in theme direction with the latter, th rollers a being forced toward wider than the part "in order, that it may.-

present a tooth area for engagement by the teeth of the gear 21 sufllciently great to carry the load? when the gear :1 acts as the driving gear: "The helix angles of the teeth on the gears 26 and 21 are made to correspond in hand and-leadito the helix angles of the rotors to which 'th igeer are respectively fixed. Regardlessofthe-speed at which the rotors turn, the gears operate to maintain the space packing referredto, thus preventing wear and permittingthe operatlon'of'the 1 pump at a, speed far exceeding any=permissible with rotors running in: contact with each other.

With the gear teeth formed in the manner shown,

the end thrust of the male rotor irotorll)" will be taken entirely through the; timing gear teeth and transferred to the female. rotor ,(rotor nawhen' the latter rotor is the driven member; The speed -c of rotation of. the'i'emale rotorin' thearrange- .4

ment shown will beso'inewhat less than :the'speed of the male rotorand-it 'wlllbe' much easier to take the end thrust of the femaleerotor with a ball bearing running atthe slowerespeed; i v A drive shaft 32 is arranged inaline'ment with the stub shaft I 6 and is provided with a"'cy1indrical portion 23, as shownin Fig.-.:6,;=journaled on a bearing sleeve 34' surroundingiahub portion 35 of the gear 21. e Keyed tojthe periphery-of the liner ring keyed, 'asat 42,Vto"the:gear'21':{The recesses 38 have relatively straight base surfaces era chamber 51 which'comml'lnicates witha conduit; '50, as "'shown in '-F'i g.' 4'; To the 3-porti56 there provided a valve OI pivotallyiiconr inected toithecasing'l at flufThisjvalvie ise ept-ed 1 normally tohbe'maintainedjopenbyia ,yen a ng at one tend the wall {of a} m .jwhich,forms a;-.porti0n of the enclosure v A chamber hilrfh-Thelother endof the V eagainst ra episton 64' vflttin'g -'a bore '65 "which is thedeeper portions of the recesses 3| and permitting rotation of the gear 21 relative to the mem- 'It win be evident that the driveshaft u is retated counterclockwise. in Fig. 2 and that the I rotors fan'd I'fturn counterclockwise and clockwise; respectively, in Fig. 8. Air taken in through ether intakeeconnection II is entrapped between the casing and the rotorseand is progressively moved and, if itremains entrapped, compressed as it is moved to the discharge chamber; ll.

material compression of -the'air take 'pla tAccordingly, there is provided "a 5! through the. casing 3 at 'su'cha point that compression of the air enclose'd between; thel otors i will-;-take place whenthe "port is unobstructed. 1Air discharged througli the port Tlfente'rs a ring 62 her 63 for the formed in a member Ii -"secured -to-the@ing 3- in. a position overlying the member-13f A" piston rodjl is ct'mujectede at its opposite en to the cylindrical portion 33 of thedi'ive shaft is a"mem'- um 0, .lfllld' u hei fi 'h pis bnfu. a d ber 31 having a number of :recesses: "formed therein receiving rollers fllwhich are-operative, as later described, at times" tozz-eilfect aclutching between the member ll andacylindrically bored thefmen ber ii icooperate in forming a- 'servowhich fluid; may be through a Pass e "anuid s uppliedte-the passege u underethe control of emeansagen'e'rally designated 110, operating in response tolpre'd eupres- 43 and radial surfaces .s1lt'will beevidentthat v a Y jv .j o m 11. Par infamy present-invention; a descripa rotation of the member in .a counterclock-j wisedirection, as viewed;in:Fig..6, cause the; rollers 39 to grip the liner-ring II and drive the gear 21. The gear 26 meshing-with the gear 21 will be driven in a-clockwise directionf andPthe' rotors I4 and 5 connected to -the g'earsji and 21 through the shafts l5 and II -will bedriven with thegeara: If the gear 21 be driven counterclock wise at a greater angular rate t eh the mem er 31, it will not be connected to that n'iember and" will turn freely in the direction mentioned rel tive to it. 7

It will be noted (Fig; 5) that the etc -s aft ll s has another shaft -48 connected to it'by" means of a splinedcOnnector, ,element 41." The-lefthand end of the shaft-lixisjournald min-beering 48 carried by, an enclosure pIate'ILaii'd the on the gear 52 is a clutch mec a fluid under pressuretoan actuat described in my applications referred'to abovei 's lre. c'c u ditions. The control :means :is described 'ili'j'myabovefmentioned applications and; since it tlon of the same is 7 considered unnecessary; a

. r s t 91 m! nven wth s provlded proved gears for driving the rotors ota pumptusi :gear; tee th are so formed as ancen the longitudinal thrust e on Lthe rotors fumein practice; it

ilgtion including lite 76 nyrotatio'n pfthe rotors-frelative togeach otherf-y if.

herein in. is vIm -t m s ific lly s'crlbed; an -For hi h-Tim n ion m rsform of the same is sh for purposesgofiillustration, and that tl ie ,inve ntion may be modified and -embodied in v'arious other iorlns *{without departing from itsspirit or th "pended E m-7 11 l t .1 i "What I-daiinas" newhnd des'ile'to securejby,

e sc p 'i apn'n nr enjg'e tojomtwithethe ether-awe -'rota-.

, eear-coaxial with fixed with respect to oneof said rotors and of the Ityisr desirable. under certain conditions'jthat no will beunderstoodthat this internga n sc ew. Weeds.-

andfor-maintainlng 5 same hand and lead as the screw threads 01' said rotor and a gear meshing with said single Bear secured to and of the same hand and lead as the screw threads of the other rotor.

2. In combination, in a pump, a casing havin an intake opening and a discharge opening, rotors in said casing having interengaging screw threads forming pockets and arranged to form, with the casing, compression spaces, means for driving one of said rotors, and means for driving the other of said rotors from the first and for maintaining them out of contact with each other during rotation including but a single gear coaxial with and fixed with respect to one of said rotors and of the same hand and lead as the screw threads oi said rotor and but a single two-part gear meshing with said single gear and secured to and of the same hand and lead as the screw threads of the other rotor.

3. In combination, in a pump, a casing having an intake opening and a discharge opening, rotors in said casing having interengaging screw threads forming pockets and arranged to iorm, with the REFERENCES CITED The following references are of record in the the of this patent:

UNITED STATES PATENTS Number Name Date 395,956 Day Jan. 8, 1889 1,755,945 Alexandrescu Apr. 22, 1930 2,014,932 Hallett Sept. 1'1, 1935 2,078,334 Martocello Apr. 2'7, 1937 2,358,815 Lysholm Sept. 26, 1944 2,369,539 Delarnere Feb. 13, 1945 

